The Dawn mission has been orbiting the asteroid Vesta since July 2011. It’s taken thousands of images of the 500 kilometer-wide (300 mile) rock since then, and JPL just released an amazing video which uses real data from Dawn to simulate flying over the asteroid.
Wow. The animation at Marcia Crater (the bottom crater making up the Snowman triple impact) is especially beautiful and realistic!
Dawn is scheduled to leave Vesta in August and then take a long, slow voyage to the even-larger asteroid Ceres, arriving in 2015. So we still have several months of riveting images of Vesta to look forward to.
Last July, the spacecraft Dawn slipped into orbit around Vesta, one of the largest asteroids in the solar system — the first time a probe had ever orbited a main-belt asteroid. From its height of 16,000 km (almost 10,000 miles), it started mapping the 500 km (300 mile) wide rock, returning the first close-up pictures in amazing detail.
Over time, the height of the spacecraft over the surface was lowered, and it has now attained its lowest altitude orbit: a mere 200 km (120 miles) over the asteroid’s cratered, battered terrain. I mean asteroidain. Whatever. Anyway, it’s now sending back higher-resolution images than ever before, including this very cool one:
[Click to asteroidenate.]
This shows a region of Vesta about 18 km (11 miles) on a side, dominated by a ginormous impact crater. You can see how the crater’s central floor is flat, and you get just a hint of a slightly raised rim around the edge of the crater. The shadow of the rim falling into the crater also suggests variations in the elevation of the rim top (though craters in the floor of the big crater distort the shadow’s edge a little too). I like all the small craters inside the big one; they come in a variety of shapes, some deep, some shallow, and one (near the rim at the bottom of the picture) appears to be sliced in half; I suspect material flowing down the crater wall in a landslide half buried it. Light colored streaks pointing down the crater wall indicate slides do occur. Triggered by other impacts, maybe?
We’ll be seeing lots of amazing images and science coming from this spacecraft over the next few months. Be sure to check the mission’s Image of the Day pages to stay on top of what we’re seeing on Vesta… but be quick, because time’s running out. In May, Dawn will leave Vesta and start a new journey for a new target: the largest asteroid in the solar system, Ceres. It arrives there in 2015.
Image credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA
By now you may have heard about this interesting video showing how many asteroids we’ve discovered since 1980. It’s pretty cool!
I have no idea how accurate it is, but the numbers seem about right; I know there are several hundred thousand known asteroids in the main belt between Mars and Jupiter [Note: the creator of the video talks about this in the comments below]. Note that a lot of the ones you see toward the end get close to Earth; according to the JPL Near-Earth Object site, almost 7200 near-Earth asteroids have been cataloged as of August 20, 2010! Of these, 815 are larger than about 1 kilometer in diameter, and 1137 are considered to be potentially hazardous; that is, have a chance (however small) of hitting the Earth.
It’s interesting to see where the asteroids are when discovered; usually in the opposite direction of the Sun, because that’s where surveys tend to look. Right at the end you’ll see two white patches at 90° from the direction of the Sun on either side. If I were a betting man — and I am — I’d wager those were from WISE, an infrared survey satellite. It scans the sky constantly, looking at right angles to the Sun, and I know it’s designed to find asteroids.
More interesting, to me, is how crowded the asteroid belt looks! But don’t be deceived. Read More